[PATCH v9 4/6] server: Allow for deletion of socket files.

[Ally Sommers]

From: Ally Sommers

Deleting the socket file is a common pattern with AF_UNIX sockets, and
is analogous to unbinding.
---
 server/fd.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/server/fd.c b/server/fd.c
index eaebe044f37..8697b07070a 100644
--- a/server/fd.c
+++ b/server/fd.c
@@ -1957,6 +1957,24 @@ struct fd *open_fd( struct fd *root, const char *name, struct unicode_str nt_nam
                 fd->unix_fd = open( name, O_RDONLY | (flags & ~(O_TRUNC | O_CREAT | O_EXCL)), *mode );
         }

+        /* open(3) throws ENXIO when `path` is one of:
+         * 1. a FIFO, and open(3) is called with O_WRONLY | O_NONBLOCK,
+         *    and no other process is currently attempting to read from `path`.
+         * 2. a special device file, and the device it corresponds to does not exist.
+         * 3. a UNIX socket.
+         * We can confirm the third case to allow for unlinking a socket.
+         */
+        if (errno == ENXIO && !stat( name, &st ) && S_ISSOCK(st.st_mode))
+        {
+            if ((access & DELETE) && unlink( name ))
+            {
+                file_set_error();
+                goto error;
+            }
+            else
+                fd->unix_fd = open( name, O_CREAT | O_RDWR, S_IRWXU );
+        }
+
         if (fd->unix_fd == -1)
         {
             /* check for trailing slash on file path */